Propagating an intelligent walker agent in a network to perform a computation

ABSTRACT

In one embodiment, a device in a network receives a path computation agent configured to determine a path in the network that satisfies an objective function. The device executes the path computation agent to update state information regarding the network maintained by the path computation agent. The device selects a neighbor of the device in the network to execute the path computation agent based on the updated state information regarding the network. The device instructs the selected neighbor to execute the path computation agent with the updated state information regarding the network. The device unloads the path computation agent from the device after selecting the neighbor of the device to execute the path computation agent.

RELATED APPLICATION

This application claims priority to U.S. patent application Ser. No.15/623,902, filed on Jun. 15, 2017, entitled INTELLIGENT WALKER AGENTSIN A NETWORK, by Levy-Abegnoli, et al., the contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to computer networks, and, moreparticularly, to intelligent walker agents in a network.

BACKGROUND

Low power and Lossy Networks (LLNs), e.g., sensor networks, have amyriad of applications, such as Smart Grid and Smart Cities. Variouschallenges are presented with LLNs, such as lossy links, low bandwidth,battery operation, low memory and/or processing capability of a device,etc. Changing environmental conditions may also affect devicecommunications. For example, physical obstructions (e.g., changes in thefoliage density of nearby trees, the opening and closing of doors,etc.), changes in interference (e.g., from other wireless networks ordevices), propagation characteristics of the media (e.g., temperature orhumidity changes, etc.), and the like, also present unique challenges toLLNs.

An example implementation of an LLN is the “Internet of Things” (IoT),which may be used by those in the art to refer to uniquely identifiableobjects/things and their virtual representations in a network-basedarchitecture. In particular, the IoT involves the ability to connectmore than just computers and communications devices, but rather theability to connect “objects” in general, such as lights, appliances,vehicles, window shades and blinds, doors, locks, etc.

Many traditional computing approaches are not applicable to LLNs and theIoT. For example, to optimize a metric along a path using a traditionalrouting approach, the prerequisite is that the topology and the relevantmetric are known by the device performing the computation. However, thelimitations of many LLN devices in terms of memory capacity, duty cycle,etc., often make such computations impossible.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments herein may be better understood by referring to thefollowing description in conjunction with the accompanying drawings inwhich like reference numerals indicate identically or functionallysimilar elements, of which:

FIG. 1 illustrate an example communication network;

FIG. 2 illustrates an example network device/node;

FIGS. 3A-3D illustrate examples of a walker agent being passed from onedevice/node to another in a network;

FIGS. 4A-4E illustrate an example of propagating a path computationagent within a network;

FIG. 5 illustrates an example simplified procedure for using a topologywalker agent to perform path computations in a network;

FIGS. 6A-6C illustrate an example of sending an agent to another networknode for execution; and

FIG. 7 illustrates an example simplified procedure for propagating awalker agent in a network according to device/node capabilities.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

According to one or more embodiments of the disclosure, a device in anetwork receives a path computation agent configured to determine a pathin the network that satisfies an objective function. The device executesthe path computation agent to update state information regarding thenetwork maintained by the path computation agent. The device selects aneighbor of the device in the network to execute the path computationagent based on the updated state information regarding the network. Thedevice instructs the selected neighbor to execute the path computationagent with the updated state information regarding the network. Thedevice unloads the path computation agent from the device afterselecting the neighbor of the device to execute the path computationagent.

Description

A computer network is a geographically distributed collection of nodesinterconnected by communication links and segments for transporting databetween end nodes, such as personal computers and workstations, or otherdevices, such as sensors, etc. Many types of networks are available,ranging from local area networks (LANs) to wide area networks (WANs).LANs typically connect the nodes over dedicated private communicationslinks located in the same general physical location, such as a buildingor campus. WANs, on the other hand, typically connect geographicallydispersed nodes over long-distance communications links, such as commoncarrier telephone lines, optical lightpaths, synchronous opticalnetworks (SONET), synchronous digital hierarchy (SDH) links, orPowerline Communications (PLC), and others. Other types of networks,such as field area networks (FANs), neighborhood area networks (NANs),personal area networks (PANs), etc. may also make up the components ofany given computer network.

In various embodiments, computer networks may include an Internet ofThings network. Loosely, the term “Internet of Things” or “IoT” (or“Internet of Everything” or “IoE”) refers to uniquely identifiableobjects (things) and their virtual representations in a network-basedarchitecture. In particular, the IoT involves the ability to connectmore than just computers and communications devices, but rather theability to connect “objects” in general, such as lights, appliances,vehicles, heating, ventilating, and air-conditioning (HVAC), windows andwindow shades and blinds, doors, locks, etc. The “Internet of Things”thus generally refers to the interconnection of objects (e.g., smartobjects), such as sensors and actuators, over a computer network (e.g.,via IP), which may be the public Internet or a private network.

Often, IoT networks operate within a shared-media mesh networks, such aswireless or PLC networks, etc., and are often on what is referred to asLow-Power and Lossy Networks (LLNs), which are a class of network inwhich both the routers and their interconnect are constrained. That is,LLN devices/routers typically operate with constraints, e.g., processingpower, memory, and/or energy (battery), and their interconnects arecharacterized by, illustratively, high loss rates, low data rates,and/or instability. IoT networks are comprised of anything from a fewdozen to thousands or even millions of devices, and supportpoint-to-point traffic (between devices inside the network),point-to-multipoint traffic (from a central control point such as a rootnode to a subset of devices inside the network), and multipoint-to-pointtraffic (from devices inside the network towards a central controlpoint).

Fog computing is a distributed approach of cloud implementation thatacts as an intermediate layer from local networks (e.g., IoT networks)to the cloud (e.g., centralized and/or shared resources, as will beunderstood by those skilled in the art). That is, generally, fogcomputing entails using devices at the network edge to provideapplication services, including computation, networking, and storage, tothe local nodes in the network, in contrast to cloud-based approachesthat rely on remote data centers/cloud environments for the services. Tothis end, a fog node is a functional node that is deployed close to fogendpoints to provide computing, storage, and networking resources andservices. Multiple fog nodes organized or configured together form a fogsystem, to implement a particular solution. Fog nodes and fog systemscan have the same or complementary capabilities, in variousimplementations. That is, each individual fog node does not have toimplement the entire spectrum of capabilities. Instead, the fogcapabilities may be distributed across multiple fog nodes and systems,which may collaborate to help each other to provide the desiredservices. In other words, a fog system can include any number ofvirtualized services and/or data stores that are spread across thedistributed fog nodes. This may include a master-slave configuration,publish-subscribe configuration, or peer-to-peer configuration.

FIG. 1 is a schematic block diagram of an example simplified computernetwork 100 illustratively comprising nodes/devices at various levels ofthe network, interconnected by various methods of communication. Forinstance, the links may be wired links or shared media (e.g., wirelesslinks, PLC links, etc.) where certain nodes, such as, e.g., routers,sensors, computers, etc., may be in communication with other devices,e.g., based on connectivity, distance, signal strength, currentoperational status, location, etc.

Specifically, as shown in the example network 100, three illustrativelayers are shown, namely the cloud 110, fog 120, and IoT device 130.Illustratively, the cloud 110 may comprise general connectivity via theInternet 112, and may contain one or more datacenters 114 with one ormore centralized servers 116 or other devices, as will be appreciated bythose skilled in the art. Within the fog layer 120, various fognodes/devices 122 may execute various fog computing resources on networkedge devices, as opposed to datacenter/cloud-based servers or on theendpoint nodes 132 themselves of the IoT layer 130. Data packets (e.g.,traffic and/or messages sent between the devices/nodes) may be exchangedamong the nodes/devices of the computer network 100 using predefinednetwork communication protocols such as certain known wired protocols,wireless protocols, PLC protocols, or other shared-media protocols whereappropriate. In this context, a protocol consists of a set of rulesdefining how the nodes interact with each other.

Those skilled in the art will understand that any number of nodes,devices, links, etc. may be used in the computer network, and that theview shown herein is for simplicity. Also, those skilled in the art willfurther understand that while the network is shown in a certainorientation, the network 100 is merely an example illustration that isnot meant to limit the disclosure.

FIG. 2 is a schematic block diagram of an example computing device/node200 that may be used with one or more embodiments described herein e.g.,as any of the devices shown in FIG. 1 above or any of the devicesdescribed further below. The device may comprise one or more networkinterfaces 210 (e.g., wired, wireless, cellular, PLC, etc.), at leastone processor 220, and a memory 240 interconnected by a system bus 250,as well as a power supply 260 (e.g., battery, plug-in, etc.).

The network interface(s) 210 contain the mechanical, electrical, andsignaling circuitry for communicating data over links coupled to thenetwork 100. The network interfaces may be configured to transmit and/orreceive data using a variety of different communication protocols. Note,further, that the nodes may have two or more different types of networkconnections 210, e.g., wireless and wired/physical connections, and thatthe view herein is merely for illustration. Also, while the networkinterface 210 is shown separately from power supply 260, for fog modulesusing PLC, the network interface 210 may communicate through the powersupply 260, or may be an integral component of the power supply. In somespecific configurations the PLC signal may be coupled to the power linefeeding into the power supply.

The memory 240 comprises a plurality of storage locations that areaddressable by the processor 220 and the network interfaces 210 forstoring software programs and data structures associated with theembodiments described herein. The processor 220 may comprise hardwareelements or hardware logic adapted to execute the software programs andmanipulate the data structures 245. An operating system 242, portions ofwhich are typically resident in memory 240 and executed by theprocessor, functionally organizes the device by, among other things,invoking operations in support of software processes and/or servicesexecuting on the device. These software processes and/or services maycomprise an illustrative “walker” agent process 248, as describedherein.

It will be apparent to those skilled in the art that other processor andmemory types, including various computer-readable media, may be used tostore and execute program instructions pertaining to the techniquesdescribed herein. Also, while the description illustrates variousprocesses, it is expressly contemplated that various processes may beembodied as modules configured to operate in accordance with thetechniques herein (e.g., according to the functionality of a similarprocess). Further, while the processes have been shown separately, thoseskilled in the art will appreciate that processes may be routines ormodules within other processes.

Routing process/services 244 include computer executable instructionsexecuted by processor 220 to perform functions provided by one or morerouting protocols, such as an Interior Gateway Protocol (IGP) (e.g.,Open Shortest Path First, “OSPF,” andIntermediate-System-to-Intermediate-System, “IS-IS”), the Border GatewayProtocol (BGP), etc., as will be understood by those skilled in the art.These functions may be configured to manage a forwarding informationdatabase including, e.g., data used to make forwarding decisions. Inparticular, changes in the network topology may be communicated amongrouters 200 using routing protocols, such as the conventional OSPF andIS-IS link-state protocols (e.g., to “converge” to an identical view ofthe network topology).

Notably, routing process 244 may also perform functions related tovirtual routing protocols, such as maintaining VRF instance, ortunneling protocols, such as for MPLS, generalized MPLS (GMPLS), etc.,each as will be understood by those skilled in the art. Also, EVPN,e.g., as described in the IETF Internet Draft entitled “BGP MPLS BasedEthernet VPN” <draft-ietf-12vpn-evpn>, introduce a solution formultipoint L2VPN services, with advanced multi-homing capabilities,using BGP for distributing customer/client media access control (MAC)address reach-ability information over the core MPLS/IP network.

Another example protocol that routing process 244 may implement,particularly in the case of LLN mesh networks, is the Routing Protocolfor Low Power and Lossy (RPL), which provides a mechanism that supportsmultipoint-to-point (MP2P) traffic from devices inside the LLN towards acentral control point (e.g., LLN Border Routers (LBRs) or “rootnodes/devices” generally), as well as point-to-multipoint (P2MP) trafficfrom the central control point to the devices inside the LLN (and alsopoint-to-point, or “P2P” traffic). RPL (pronounced “ripple”) maygenerally be described as a distance vector routing protocol that buildsa Directed Acyclic Graph (DAG) for use in routing traffic/packets 140,in addition to defining a set of features to bound the control traffic,support repair, etc. Notably, as may be appreciated by those skilled inthe art, RPL also supports the concept of Multi-Topology-Routing (MTR),whereby multiple DAGs can be built to carry traffic according toindividual requirements.

Intelligent Walker Agents in a Network

As noted above, many devices/nodes in constrained networks, such as LLNsand the IoT, have very limited resources in terms of available memory,processing power, power source (e.g., battery charge, etc.), and thelike. Accordingly, such devices may not be able to locally perform manycomputationally-intensive tasks. This is particularly true in cases inwhich the processing device/node is required to maintain stateinformation for multiple devices/nodes in the network.

To address the various limitations of constrained devices in certainnetworks, existing approaches rely on the deployed devices leveraging amore capable device to perform the computations. For example, thedevices in the network could offload the computations to a remote serveror cloud-based service outside of the local network. However, doing soalso increases the amount of bandwidth consumed to relay the informationto and from such a server or service (e.g., via a WAN connection). Amore recent evolution proposes the use of the local networking devices,such as edge routers, to perform the computations in the “fog.”

According to various embodiments, the concept of a “walker agent” isintroduced herein and offers yet another alternative approach toperforming more complex computations in a network of constraineddevices/nodes. In general, a walker agent refers to a software agentthat loads and executes on a particular device/node in a network,updates state information for its computation during execution, passesboth its executable code and updated state information to the nextdevice/node in the network for execution, and then unloads/removes itslocal copy of the agent. In other words, execution of a walker agent“hops” from one device in the network to the next, while maintaining thestate information for its computations during these transfers.

FIGS. 3A-3D illustrate examples of a walker agent being passed from onedevice/node to another in a network. As shown, consider the case of twodevices, device 302 a and device 302 b, both located in a network 300.In some cases, devices 302 a-302 b may be neighboring devices having adirect communication link there between. In other cases, devices 302a-302 b may be separated by any number of intermediate devices thatrelay communications between devices 302 a-302 b.

During operation, device 302 a may receive walker agent 304 from anotherdevice in the network, such as a neighbor of device 302 a, anotherconstrained device along a routing path in the network, or from asupervisory device that provides administrative control over device 302a. In various embodiments, walker agent 304 may comprise executable code306, as well as state information 308.

As shown in FIG. 3A, device 302 a may load executable code 306 whichperforms a particular computation for which it was configured andupdates state information 308, accordingly. Generally, state information308 may be a set of one or more parameter values that reflect thecurrent state of the computation performed by executable code 306. Suchvalues may be one or more observations about device 302 a (e.g., theneighbors of device 302 a, the signal strengths to the neighbors, etc.),the portion of network 300 around device 302 a, and/or computed valuesderived therefrom (e.g., averages, statistics, maxima or minima,gradients, etc.).

For example, assume that executable code 306 is configured to calculatean optimal value or running total at each hop or at specific pointsalong a networking path, based on the locally observable value(s) ateach device. In such a case, when device 302 a receives walker agent304, it may load and execute executable code 306 of walker agent 304, toretrieve its own locally observable value(s), perform the associatedcomputations on them, and update state information 308, accordingly.

As shown in FIGS. 3B-3C, once device 302 a has executed walker agent304, thereby updating state information 308 into updated stateinformation 308 a, device 302 a may send walker agent 304 to device 302b. In doing so, when device 302 b executes code 306 of walker agent 304,walker agent 304 is able to continue its computation from the point atwhich it left off on device 302 a. In other words, device 302 b may thenload walker agent 304 and update state information 308 a using its ownlocal information. Once completed, device 302 b may then send walkeragent 304 on to the next device in the network, to repeat the process.

In FIG. 3D, another key aspect of a walker agent is that its executionmay “hop” from device to device in the network, in various embodiments.Notably, after walker agent 304 has been passed to device 302 b, device302 a may unload walker agent 304 from its local system, thereby freeingup resources on device 302 a. In some embodiments, this may entaildeleting or otherwise removing walker agent 304 from 302 a after walkeragent 304 has been passed to device 302 b for execution. In other words,at any given time, a walker agent may be executed by a subset of one ormore devices in the network that changes over the course of time as theexecuting device(s) complete their computations.

Various use cases for a walker agent are described below as examples ofcomputations that could not otherwise be performed by constraineddevices in a network. As would be appreciated, these examples areprovided for illustrative purposes only and are not intended to belimiting.

Path Computation in a Network Using a Topology Walker

In many traditional routing protocols, when an objective function forone or more metrics needs to be satisfied/optimized for a routing path,a prerequisite is that the node performing the path computation alreadyknows the topology of the network and the relevant metric(s). Forexample, the node performing the path computation may seek to find anetwork path that minimizes the number of hops, or satisfies apredefined threshold in terms of delay, jitter, or bandwidth along thepath. Any number of other objective functions can also be used forpurposes of path selection.

To perform the path computations using many existing protocols, twodifferent approaches are typically taken. In one approach, the entireset of information (e.g., topology information, observed metrics, etc.)may be flooded throughout the network, to disseminate the informationthrough the graph of nodes. For example, if the computed result is to beused for forwarding, such as via the shortest network path, each nodeindividually computes the optimal path for the metric, and repeat thatoperation regularly. In the alternate approach, the information is madeavailable to a path root, which can perform source routing for theoptimized metric.

When attempting to implement existing network protocols in an LLN, suchas an IoT network, both the required local computations and transfer ofinformation between nodes may be too cumbersome for the constraineddevices/nodes in the network. For example, a set of temperature sensorsmay not have the storage capacity to store large amounts of networkstate needed to perform path computations and/or to send stateinformation to a central path computation engine (PCE). Notably, manydevices in an LLN or IoT network are characterized by having lowprocessing and storage capabilities, limited bandwidth, constrained dutycycles and power sources (e.g., many are battery powered), and the like.

The techniques herein introduce a software agent module that canphysically “walk” within a network, to compute a path that satisfies anobjective function (e.g., in terms of number of hops, jitter, delays,battery, temperature, etc.). In doing so, the metric and topologyinformation does not need to be propagated throughout the network ormaintained by a sole device in the network. This allows many constrainednodes, such as LLN/IoT nodes, to still contribute to the pathcomputation.

Specifically, according to one or more embodiments of the disclosure asdescribed in detail below, a device in a network receives a pathcomputation agent configured to determine a path in the network thatsatisfies an objective function. The device executes the pathcomputation agent to update state information regarding the networkmaintained by the path computation agent. The device selects a neighborof the device in the network to execute the path computation agent basedon the updated state information regarding the network. The deviceinstructs the selected neighbor to execute the path computation agentwith the updated state information regarding the network. The deviceunloads the path computation agent from the device after selecting theneighbor of the device to execute the path computation agent.

Illustratively, the techniques described herein may be performed byhardware, software, and/or firmware, such as in accordance with the“walker” agent process 248, which may include computer executableinstructions executed by the processor 220 (or independent processor ofinterfaces 210) to perform functions relating to the techniquesdescribed herein, e.g., in conjunction with routing process 244.

Operationally, the proposed techniques sharply change the paradigm withrespect to path computations. In various embodiments, instead of eachnode sending its information to the point of computation, such as toeach node, to the network root, to a PCE, etc., a software-based, pathcomputation “walker” agent may traverse the topology of the network toperform the path computation. In general, as referred to herein, a“walker” agent refers to a signed piece of software that can be executedsecurely when it is installed in a given device/node, together withwhatever state it carries at the time of execution, and that can copy ortransfer itself to an adjacent/neighboring node, together with itsstate. For example, in the case of a path computation agent, each nodethat executes the agent may attempt to optimize the objective functionand update the state maintained by the agent regarding the network,before having the agent “walk” to a selected neighbor of the node forexecution. In particular, instead of exploring the topology graph forthe network at the executing node, which requires the topology andmetrics to be known by the node, the agent explores the topology graphby physically moving its execution from node to node within the networkitself, which only requires each executing node to know its neighbors.

Any number of different approaches can be used to have the pathcomputation agent physically moves its execution from node to nodewithin the network (e.g., Dijkstra's, Bellman-Ford, etc.). Because ofthis movement of the execution of the agent between the various membersof the network, it may also entail the agent backtracking occasionally,such as when a path segment is found non-optimal for the metric.Notably, when the path computation agent reaches a node, and is loadedand executed by that node, the agent may use its maintained stateregarding the network (e.g., accumulated path metrics, etc.) todetermine that the latest accumulated metric is sub-optimal compared tothe current best one. In such a case, the node may pass execution of theagent back to its neighbor from which it was received and/or try anotherneighbor, instead. The agent can, in various cases, keep a state ofwhich neighbors have been explored or, alternatively, store that statein the node itself.

FIGS. 4A-4E illustrate an example of propagating a path computationagent within a network, according to various embodiments. As shown inFIG. 4A, assume that there are nodes/devices 132 a-132 f within networkportion 400 (e.g., a portion of network 100) that are interconnected bylinks 404. In various embodiments, a path computation agent may “walk”the nodes 132 a-132 f, in order to identify a path in network segment400 that optimizes a defined objective function (e.g., optimizes one ormore network metrics). As noted above, “walking” herein generally refersto the repetitive process of unloading the agent after execution on agiven node and loading the agent on a neighbor of the node forexecution.

In FIG. 4A, assume that node 132 a is the first node 132 in networkportion 400 to execute the path computation agent. Thus, the agent atthis point in time has no state information regarding network portion400. Node 132 a may load the agent module either directly or in avirtualized manner, such as in a container (e.g., Docker container,etc.) or in a virtual machine (VM). Such a module may include theexecutable agent itself and/or the state information for the executingagent (e.g., information gathered by the agent regarding the network).In some embodiments, node 132 a may receive the agent for execution fromanother node or a supervisory device. In other embodiments, the agentmay be preexisting on node 132 a and remain dormant and unloaded untilexecution time.

Once loaded by node 132 a, the path computation agent may build aneighbor list L of the nodes that neighbor node 132 a as part of itsstate information regarding the network. In other words, the agent mayfirst identify the neighbors of node 132 a, nodes 132 b and 132 c, forinclusion in the list. Neighbor discovery can be achieved using any ofthe various wireless and neighbor discovery protocols available.

From the identified neighbors list, the path computation agent mayassess the metrics associated with the neighbors of node 132 a, such asmetrics regarding their respective links 404. To then explore furtherinto the topology of network portion 400, the agent may select one ofthe neighbors, such as 132 c shown, to next execute the path computationagent. For example, the agent may pop node ‘C’ (e.g., node 132 c) fromthe neighbor list and save the current and accumulated metrics as partof the state maintained by the agent. In turn, node 132 a may send theagent module 402 on to node 132 c that includes the state informationmaintained by the path computation agent, such as the current neighborlist (e.g., topology information) and metrics (e.g., current andaccumulated). In other words, node 132 a may instruct its neighboringnode 132 c to load and execute the path computation agent and using theinformation in module 402. After selecting the neighbor node 132 c tonext load and execute the agent (e.g., before or after instructing node132 c to next load and execute the agent), node 132 a may unload theagent from itself, thereby again freeing resources on node 132 a.

In FIG. 4B, node 132 c load and execute the path computation agent usingthe state information received from node 132 a. In turn, the agentexecuting on node 132 c may identify the neighbors of node 132 c, nodes132 d and 132 f, update the neighbor list maintained by the agent, andassess their respective metrics. In particular, the agent may assessthese metrics in view of the metrics sent by node 132 a as part ofmodule 402, to see whether exploration of either neighbor represents anoptimal next step or, alternatively, whether execution of the agentshould backtrack to node 132 a (e.g., for exploration of node 132 binstead).

Assume, for purposes of illustration, that the agent executing on node132 c determines that node 132 d should next be explored. Accordingly,the agent may pop node ‘D’ (e.g., node 132 d) from its neighbor list,and send agent module 402 with the updated state information to node 132d, thereby instructing node 132 d to load and execute the agent. Inturn, node 132 c may unload its copy of the agent.

In FIG. 4C, node 132 d may then operate in a similar manner as that ofnode 132 c, loading and executing the agent with the state informationreceived from node 132 c. Notably, node 132 d may identify itsneighbor(s), update the neighbor list of the agent, and assess themetrics in view of the objective function. If the agent determines thatexploring node 132 f is the next optimal step, node 132 d may send theagent module 402 with the updated state/topology information to node 132f, thereby instructing node 132 f to load and execute the agent locallyusing the received information. In turn, node 132 d may unload its copyof the agent, to free up resources.

In FIG. 4D, node 132 f may load and execute the agent with the receivedinformation from node 132 d. In turn, node 132 f may identify its ownneighbors, update the state information, and determine that node 132 eis the next optimal hop to explore in view of the metrics observed thusfar by the walking agent. If so, node 132 f may send module 402 on tonode 132 e with the updated state information for loading and executionby node 132 e. To complete the “walking” action, node 132 f may alsounload the agent from itself, to free up its own resources.

In FIG. 4E, assume now that the path computation agent loaded andexecuted by node 132 e explores the neighbors of node 132 e anddetermines that the metrics associated with traversing the link 404 tonode 132 b would be sub-optimal in view of the metrics for the exploredsegments thus far. In such a case, node 132 e may determine that theagent should backtrack to node 132 f. Thus, node 132 e may send theagent module 402 with its updated information back to node 132 f, fromwhich node 132 e received module 402, thereby instructing node 132 f toagain load and execute the agent. Node 132 e may also unload itsexecuting copy of the agent, returning execution of the agent to node132 f.

As the agent makes its way through network portion 400, each node maymark the path, so that the node knows where to forward network trafficreceived by the node. In various embodiments, the path computation agentmay regularly walk through the nodes of network portion 400, such aswhen a change in the network is detected. For example, when a nodedetermines that a link cost has changed significantly (e.g., by acertain percentage, a predefined delta, etc.), the node may again loadand execute the path computation agent, to walk the local disturbanceand re-compute the affected paths. In various cases, the agent mayremain dormant/unloaded on the node or, alternatively, the node mayagain request the path computation agent, when a change in the networkis detected.

Note that by propagating the path computation agent from node to nodewithin the network, the topology does not need to be distributedthroughout the network, which may be very resource-consuming for largetopologies. Further, no node in the network need store the entiretopology. In an LLN or IoT network (e.g., a sensor network), with a verylarge number of nodes, storing the topology may require more memory thanavailable on the nodes.

In further embodiments, the agent may replicate itself to explorebranches of the topology in parallel, thereby speeding up the overallpath computation. When replicating, the two (or more) agents may agreeto meet at a rendezvous point in the network (e.g., a selected node),which will then merge the information from the agents (e.g., by mergingtheir maintained state information). For example, when a replica visitsa node that was already visited by one of its clones, it may compare thecost that the clone found for the path to that node and if the previouscost was better or for a newer iteration (e.g., as indexed by a sequencenumber and the ID of the node that started the computation when it foundthe disturbance and/or the time when the disturbance was found) thenthis replica dies there (e.g., unloads/exits). If the replica brings ina better cost, it overrides the previous state.

Said differently, the techniques herein introduce a “walking agent” thatdoes not run on one CPU, and does not require full knowledge of thenetwork topology, to make path computations. Instead, the agent movesitself (physically) from one node to the next, carrying previouslycomputed states, to execute some logic on each node, which depends onalready computed states and the local situation. All that is requiredfor a node is to know its immediate neighbor, but never needs to sendsthis information. When the agent leaves a node for the next, it marksthe route and a few other states. When the agent is done walking thenetwork (circulating on it), the situation on each node is the very sameas if each node had the full topology and ran the same path computationfrom a global perspective.

FIG. 5 illustrates an example simplified procedure for using a topologywalker agent to perform path computations in a network, in accordancewith one or more embodiments described herein. For example, anon-generic, specifically configured device (e.g., device 200) mayperform procedure 500 by executing stored instructions (e.g., process248). The procedure 500 may start at step 505, and continues to step510, where, as described in greater detail above, the device may receivea path computation agent configured to determine a path in the networkthat satisfies an objective function. The objective function may, forexample, attempt to optimize one or more metrics for a network path,such as the number of hops, delay, jitter, hop resources (e.g., in termsof CPU, memory, battery, etc.), combinations thereof, or the like. Ingeneral, the path computation agent may be a “walker” agent that getsexecuted by different nodes at different times, thereby allowing theagent to walk from one node/device to another by switching its executingdevice. In some cases, the device may also receive state informationregarding the network from another device/node that previously executedthe agent.

At step 515, as detailed above, the device may execute the pathcomputation agent to update state information regarding the networkmaintained by the path computation agent. For example, the executingagent may identify any neighbors of the device, determine any metricsassociated with the links thereto, calculate aggregated metrics, and/orcompare the updated metrics to those received by the device. If, forexample, the device determines that a given link to its neighbor wouldhave an aggregated metric that is worse than the current aggregatedmetric, the device may determine that the agent should backtrack to theneighbor from which the device received the agent.

At step 520, the device may select a neighbor to execute the pathcomputation agent based on the updated state information, as describedin greater detail above. Notably, if the link to one of the neighbors ofthe device offers a currently-optimal path in view of the objectivefunction, the node may select that neighbor as the next node for thepath computation to explore.

At step 525, as detailed above, the device may instruct the selectedneighbor to execute the path computation agent using the updated stateinformation regarding the network (e.g., as updated by the device). Forexample, in some cases, the instruction may include the stateinformation (e.g., the metrics and topology information thus farobtained by the walking agent) and/or the code for the agent itself.Such an instruction may cause the receiving neighbor to load and executethe path computation agent using the state information sent by thedevice, thus “walking” the agent to the neighbor for further execution.

At step 530, the device may unload the path computation agent from thedevice after selecting the neighbor of the device to execute the pathcomputation agent, as described in greater detail above. In some cases,the device may unload the agent after its state information is updated.In other cases, the device may wait for successful transmission of theinstruction to the neighbor to begin executing the agent, beforeunloading the local copy of the agent. Procedure 500 then ends at step535.

It should be noted that while certain steps within procedure 500 may beoptional as described above, the steps shown in FIG. 5 are merelyexamples for illustration, and certain other steps may be included orexcluded as desired. Further, while a particular order of the steps isshown, this ordering is merely illustrative, and any suitablearrangement of the steps may be utilized without departing from thescope of the embodiments herein.

Propagating an Intelligent Walker Agent to Perform a Computation

Another potential use case for walker agents addresses cases in which adevice/node in the network is unable to perform a certain computationlocally. As noted above, LLNs exhibit a number of different constraintsthat are not typically found in traditional networks, such as verylimited node resources in terms of CPU, power source (e.g., battery orscavenged), and the like. In some cases, resources on a node may be soconstrained that the node cannot complete the required computation, suchas computing a network path, locating itself with GPS, signing orverifying a piece of data, etc. One potential way to address this is toperform the node's computations on a supervisory device, such as a PCE.However, this is only applicable in situations in which the data is notoverly time-sensitive. For example, in the case of an instantaneoustemperature, or the like, the data returned back to the node may alreadybe outdated for use.

In further embodiments of the techniques herein, a node may leverage awalking agent to offload certain computations, such as the pathcomputations described previously. In particular, the walking agent maytraverse the network until it finds a node that can execute the agentor, in some cases, split the agent into smaller agents and either runthem or spread them again.

Illustratively, the techniques described herein may be performed byhardware, software, and/or firmware, such as in accordance with the“walker” agent process 248, which may include computer executableinstructions executed by the processor 220 (or independent processor ofinterfaces 210) to perform functions relating to the techniquesdescribed herein, e.g., in conjunction with routing process 244.

FIGS. 6A-6C illustrate an example of sending an agent to another networknode for execution, according to various embodiments. As shown in FIG.6A, assume that the nodes 132 a-132 f are part of a routing topology DAG602, whereby links 404 have already been selected to form the paths inthe network via which traffic is to be sent. Such a DAG 602 may beformed, for example, by employing RPL or another such protocol withinthe network.

As shown in FIG. 6A, assume that node 132 a determines that it cannotexecute a given computational task on its own. This may be due, forexample, to a lack of a particular resource available on node 132 a(e.g., CPU, battery reserves, etc.), or because the computation is of atype that can be partially offloaded through collaboration between node132 a and one or more other nodes 132 in the network. Assume, further,that node 132 a is aware of its neighbors and their capabilities,through some neighbor discovery protocol. For example, the node 132shown may use the Cisco Discovery Protocol (CDP), Link Layer DiscoveryProtocol (LLDP), or the like, to discover their neighbors and thecapabilities of their neighbors

Based on determining that node 132 a is not able to perform a givencomputational task, it may package the state information required forthis computation and the computational software/agent as part of anagent module 604. In turn, node 132 a may sign agent module 604 and sendit to a neighbor (e.g., node 132 b) selected by node 132 a.

In some embodiments, if the computation is to be ran locally, because ituses some local metric that could not be measured remotely, or wouldtake too long to be transmitted there, the requester node 132 a can addsome execution constraint into its packaged request/agent module 604(e.g., such as distance from the node). Then, not all neighbor areexplored but only those which (cumulatively) comply with theconstraints.

In another embodiment, the initial task could also be split into severalatomic ones, and be executed on different nodes, so the process usesrecursion on smaller items to determine the final results.

If node 132 b can execute the agent, it may do so and send the resultsback to node 132 a. However, as shown in FIG. 6B, if node 132 b alsodetermines that it cannot perform the computation for whatever reason,node 132 b may send agent module 604 on to one or more of its ownneighbors, such as node 132 e. This walking process may repeat itselfrecursively until one or more suitable nodes receive the agent module604.

As shown in FIG. 6C, assume now that node 132 e has received agentmodule 604 and has the proper resources available to make thecomputation using the state information from node 132 a. In turn, node132 e may execute the agent with the state information and return thecomputed results 406 back to node 132 a. Since there is already aDAG/graph established in the network, the first node in the network thatcan do the job may send the result, which is then relayed back to therequestor. This way, only one node at a time is given the executiontoken. Results 406 can be, for example, packaged as another signedobject and shipped back over a path that reverses the lookup describedabove (e.g., in a reverse direction along DAG 602).

In some embodiments, when a node is done exploring it neighbors with noluck, it may send a failure notification back to its own DAG parent,which can then try another neighbor of the parent, instead. If none ofthe nodes at all can execute the task, the requester will get failurefrom all of its neighbors and can declare general failure.

Thus, by leveraging the concept of a walker agent, a constrained nodethat cannot perform the entire computation locally can package the agentand state information for execution by one or more of its neighbors orother close by nodes in the network. For example, a set of IoT or otherconstrained devices may expose a set of application program interfaces(APIs) that a walker agent can use, e.g., to obtain a measurement,trigger an action, read a diagnostic, etc.

FIG. 7 illustrates an example simplified procedure for propagating awalker agent in a network according to device/node capabilities, inaccordance with one or more embodiments described herein. For example, anon-generic, specifically configured device (e.g., device 200) mayperform procedure 700 by executing stored instructions (e.g., process248). The procedure 700 may start at step 705, and continues to step710, where, as described in greater detail above, the device maydetermine that is incapable of performing a particular computation. Insome embodiments, for example, the device may determine that it does nothave sufficient resources to perform the computation (e.g., in terms ofmemory, processing power, available battery charge, etc.) or does notsatisfy a policy associated with the computation (e.g., a securitypolicy, a resource policy, etc.).

At step 715, as detailed above, the device may generate an executablewalker agent configured to perform the particular computation. In someembodiments, the device may generate the agent to also include stateinformation that can be used by the agent during execution to performthe computation. For example, the state information may comprise one ormore measurements, statistics, or other parameters from the device. Inanother example, the state information may comprise the currentparameter state of the computation, such as when the device has alreadystarted the computation but cannot finish.

At step 720, the device may send the executable agent to one or moreother devices in the network, as described in greater detail above. Inresponse to receiving the agent, the one or more other devices in thenetwork may execute the agent to perform the particular computation anddetermine a result of the particular computation. In some embodiments,the other devices may also determine whether they themselves can executethe agent and, if not, may send the agent on towards further devices inthe network. For example, if the device sends the agent to one of itsneighbors for execution, and the neighbor is unable to execute theagent, the neighbor may pass the agent on to one of its own neighborsfor execution. In some embodiments, the device may send the agent to theother device(s) with execution constraints that may be used by areceiving device to determine whether to execute the agent. For example,such constraints may be temporal (e.g., only execute the agent within acertain timeframe or if the result can be sent back to the device withina certain timeframe, etc.), locational (e.g., only execute the agent ifthe executing device is within a certain path distance to the device,etc.), capability-based (e.g., only execute the agent if the executingdevice has a predefined amount of resources available, etc.),combinations thereof, or the like.

At step 725, as detailed above, the device may receive a result of thecomputation from one or more of the other device(s) that execute thesent agent. Thus, while the device itself is incapable of performing thecomputation, the one or more other agents may perform the computation onits behalf and return the result back to the device. Note that doing somay be far more localized within the network than by leveraging a fogcomputing or cloud-based approach, which is of particular importance fortime-sensitive computations. Procedure 700 then ends at step 730.

It should be noted that while certain steps within procedure 700 may beoptional as described above, the steps shown in FIG. 7 are merelyexamples for illustration, and certain other steps may be included orexcluded as desired. Further, while a particular order of the steps isshown, this ordering is merely illustrative, and any suitablearrangement of the steps may be utilized without departing from thescope of the embodiments herein. Further, while procedures 500 and 700are described separately, some or all of their respective steps may beintegrated into one another, in further embodiments.

The techniques described herein, therefore, introduce various “walker”agents that may physically move between different executingnodes/devices within the network. In some aspects, a path computationwalker agent may be used, allowing an optimal path to be computedwithout having to distribute the entire topology and metric informationfor the entire network. In further aspects, a walker agent may also moveto more capable nodes in the network, if the current node does not havethe resources to execute the agent.

While there have been shown and described illustrative embodiments thatprovide for deploying a walker agent within a network, it is to beunderstood that various other adaptations and modifications may be madewithin the spirit and scope of the embodiments herein. For example,while certain protocols are shown, such as RPL, other suitable protocolsmay be used, accordingly.

The foregoing description has been directed to specific embodiments. Itwill be apparent, however, that other variations and modifications maybe made to the described embodiments, with the attainment of some or allof their advantages. For instance, it is expressly contemplated that thecomponents and/or elements described herein can be implemented assoftware being stored on a tangible (non-transitory) computer-readablemedium (e.g., disks/CDs/RAM/EEPROM/etc.) having program instructionsexecuting on a computer, hardware, firmware, or a combination thereof.Accordingly, this description is to be taken only by way of example andnot to otherwise limit the scope of the embodiments herein. Therefore,it is the object of the appended claims to cover all such variations andmodifications as come within the true spirit and scope of theembodiments herein.

What is claimed is:
 1. A method comprising: determining, by a device ina network, that the device is incapable of performing a particularcomputation; generating, by the device, an executable agent configuredto perform the particular computation; sending, by the device, theexecutable agent to one or more other devices in the network, whereinthe one or more other devices in the network execute the agent toperform the particular computation and determine a result of theparticular computation; and receiving, at the device, the result of theparticular computation from at least one of the one or more otherdevices in the network that execute the agent.
 2. The method as in claim1, wherein determining that the device is incapable of performing theparticular computation comprises: determining, by the device, that thedevice does not have sufficient resources available to perform theparticular computation or does not satisfy a policy associated with thecomputation.
 3. The method as in claim 1, wherein generating theexecutable agent configured to perform the particular computationcomprises: digitally signing, by the device, the executable agent. 4.The method as in claim 1, wherein generating the executable agentconfigured to perform the particular computation comprises: including,by the device, state information with the executable agent for use whendetermining the result of the particular computation.
 5. The method asin claim 1, wherein sending the executable agent to the one or moreother devices in the network comprises: including, by the device, one ormore execution constraints with the sent executable agent that controlwhether a given receiving device executes the agent.
 6. The method as inclaim 5, wherein the one or more execution constraints comprise at leastone of: a time limit to return the result to the device or a pathdistance to the device.
 7. The method as in claim 1, wherein sending theexecutable agent to the one or more other devices in the networkcomprises: sending, by the device, the executable agent to a neighbor ofthe device in the network for execution.
 8. The method as in claim 7,wherein the neighbor of the device determines that it is incapable ofexecuting the agent and propagates the agent within the network untilthe agent is received by a device capable of executing the agent.
 9. Themethod as in claim 1, further comprising: splitting, by the device, theparticular computation into a plurality of sub-computations; generating,by the device, a plurality of executable agents to perform thesub-computations; and sending, by the device, the plurality ofexecutable agents to the one or more other devices in the network forexecution.
 10. An apparatus, comprising: one or more network interfacesto communicate with a network; a processor coupled to the networkinterfaces and configured to execute one or more processes; and a memoryconfigured to store a process executable by the processor, the processwhen executed configured to: determine that the apparatus is incapableof performing a particular computation; generate an executable agentconfigured to perform the particular computation; send the executableagent to one or more other devices in the network, wherein the one ormore other devices in the network execute the agent to perform theparticular computation and determine a result of the particularcomputation; and receive the result of the particular computation fromat least one of the one or more other devices in the network thatexecute the agent.
 11. The apparatus as in claim 10, wherein theapparatus determines that the apparatus is incapable of performing theparticular computation by: determining that the apparatus does not havesufficient resources available to perform the particular computation ordoes not satisfy a policy associated with the computation.
 12. Theapparatus as in claim 10, wherein the apparatus generates the executableagent configured to perform the particular computation by: digitallysigning the executable agent.
 13. The apparatus as in claim 10, whereinthe apparatus generates the executable agent configured to perform theparticular computation by: including state information with theexecutable agent for use when determining the result of the particularcomputation.
 14. The apparatus as in claim 10, wherein the apparatussends the executable agent to the one or more other devices in thenetwork by: including one or more execution constraints with the sentexecutable agent that control whether a given receiving device executesthe agent.
 15. The apparatus as in claim 14, wherein the one or moreexecution constraints comprise at least one of: a time limit to returnthe result to the apparatus or a path distance to the apparatus.
 16. Theapparatus as in claim 10, wherein the apparatus sends the executableagent to the one or more other devices in the network by: sending theexecutable agent to a neighbor of the apparatus in the network forexecution.
 17. The apparatus as in claim 10, wherein the neighbor of theapparatus determines that it is incapable of executing the agent andpropagates the agent within the network until the agent is received by adevice capable of executing the agent.
 18. The apparatus as in claim 10,wherein the process when executed is further configured to: split theparticular computation into a plurality of sub-computations; generate aplurality of executable agents to perform the sub-computations; and sendthe plurality of executable agents to the one or more other devices inthe network for execution.
 19. A tangible, non-transitory,computer-readable medium storing program instructions that, whenexecuted by a device in a network to perform a process comprising:determining, by the device in the network, that the device is incapableof performing a particular computation; generating, by the device, anexecutable agent configured to perform the particular computation;sending, by the device, the executable agent to one or more otherdevices in the network, wherein the one or more other devices in thenetwork execute the agent to perform the particular computation anddetermine a result of the particular computation; and receiving, at thedevice, the result of the particular computation from at least one ofthe one or more other devices in the network that execute the agent. 20.The computer readable medium as in claim 19, wherein sending theexecutable agent to the one or more other devices in the networkcomprises: including, by the device, one or more execution constraintswith the sent executable agent that control whether a given receivingdevice executes the agent.